1. Field of the Invention
Embodiments of the invention generally relate to metallization of large area substrates.
2. Background of the Related Art
Integrated circuits typically include a plurality of devices formed from dielectric, conductive and semiconductive material. Conductive materials, such as metals, are typically deposited on a substrate by chemical vapor deposition, physical vapor deposition, electroplating and electroless plating.
Electroless plating has generated interest due to its ability to produce highly conformal selective deposition without the requirement of a vacuum chamber. This is particularly attractive for the metallization of large area substrates (i.e., substrates in excess of about 1 meter square) where the chamber costs and associated vacuum pump hardware may become prohibitively expensive, particularly if market demands for substrates exceeding 1.5 square meters are to become realized.
One method for patterning metal on substrates using electroless deposition is microcontact printing. Microcontact printing typically entails applying a precursor or catalyst to the substrate surface using a patterned elastomeric stamp. The catalyst is typically a self-aligning monomer that remains highly ordered on the substrate surface. An electrolyte solution is then applied to the substrate and deposits a layer of metal on the catalyst sites, thereby creating a patterned metal line. Although the use of microcontact printing and electroless deposition has been demonstrated as being capable to produce conductive lines on substrates having diameters of 8 inches or less, its applicability to large area substrates remains unproven. For example, the ability to transfer the catalyst from the stamp over a large surface area on a flexible large area substrate has not been demonstrated. Moreover, a method for the application of the catalyst to a large area substrate in a production environment has not been developed. Additionally, a method to overcome the capillary forces between the stamp and the substrate must be developed in order to separate the substrate from the stamp.
Therefore, there is a need for a method and apparatus for electroless plating of large area substrates.